In many areas of industry there is a need for a cleaning method and apparatus capable of removing oil components from articles of manufacture. For example, cleaning is often required of motors, food processing machines, other metal, ceramic, plastic and painted surfaces that may become soiled with oily components and adhesive residues. Specifically, in the manufacture of articles, such as metal articles, it is common for oil-based compositions to be used as lubricants, forming oils and/or coolants during the manufacturing process. It is frequently necessary to clean such manufactured articles of the oil-based compositions prior to subsequent steps, such as coating or decorating the surfaces of the article. Commonly, such manufacturing oils are cleaned with either acidic or caustic solutions, chlorinated solvents or petroleum based cleaners and subsequently rinsed with water for cleaning. Such cleaning processes have a number of disadvantages including, health hazards and hazards in handling acidic or caustic solutions, the need for treatment and disposal of used wash solutions to comply with environmental regulations prior to their discharge, and damage caused to the articles being cleaned.
The use of nonhazardous, nontoxic, noncorrosive biodegradable cleaning products would be preferable over the many industrial cleaning solvents currently in use. It has been recognized in related applications that terpene-based cleaning compositions are particularly advantageous for cleaning oil-based compositions from manufactured articles. For example, in specific processes, such as the manufacture of cans, it has been found that terpene-based cleaning compositions cause significantly less etching when compared with acidic or caustic wash solutions. Such reduced etching results in highly improved reflectivity of containers, increased mobility of articles on conveyor lines, the ability to recycle various liquid streams in the cleaning system, and the ability to use decreased amounts of coatings necessary to decorate or protect cleaned articles.
A problem encountered in terpene-based cleaning systems is that to recycle the cleaning solution, contaminants which have been removed from articles must be separated from the contaminated cleaning solution prior to recycling and reuse of the cleaning solution. However, it has been found that many terpene-based cleaning systems do not allow for the efficient and effective separation of contaminants from cleaning agents and compositions. Moreover, the separation of water that has been mixed with oils and/or cleaning agents is necessary to enable such water to be reused, as well as to concentrate undesired contaminants for economical disposal.
A method and apparatus is required to facilitate the effective and economical separation of terpene cleaning agents from oils, and to facilitate the recycling of liquid streams, particularly aqueous streams and terpene cleaners used in the cleaning processes.